In a magnetic resonance imaging system, magnetic resonance (MR) signals are received using receiving coils, and analog-to-digital conversion and digital down-conversion processing are performed on the magnetic resonance signals from the receiving coils using a digital receiver system to obtain corresponding magnetic resonance imaging signals.
In practical applications, a plurality of receiving coils may be set in an array form, and receiving magnetic resonance signals using the receiving coil array may improve the signal-to-noise ratio of the received magnetic resonance signals, and may better meet the requirements of clinical applications. Each receiving coil in the receiving coil array may be referred to as a coil unit of the array.
To obtain corresponding magnetic resonance imaging signals, a digital receiver system may perform low noise amplification, filtering and frequency mixing on the magnetic resonance signals from each coil unit to obtain intermediate frequency signals borne on a certain carrier frequency of one channel. After performing amplification, filtering and compression on the intermediate frequency signals, the intermediate frequency signals are output to an analog-to-digital conversion unit (ADC) to perform digital sampling so as to obtain digital domain signals. Down-conversion processing is performed on the digital domain signals using a digital processing unit such as a data signal processor (DSP) or a field programmable gate array (FPGA).
With the requirements of clinical applications and the development of the technology of receiving coils (e.g., the number of coil units in a receiving coil array is increasing), the signal-to-noise ratio (SNR) and degree of uniformity of the image obtained thereby are correspondingly greatly improved. However, the increase in the number of coil units will increase the number of channels that bear signals and the number of corresponding ADCs, and correspondingly increase the system costs.